EP0261854B1 - Rack and pinion gear - Google Patents

Rack and pinion gear Download PDF

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Publication number
EP0261854B1
EP0261854B1 EP87308111A EP87308111A EP0261854B1 EP 0261854 B1 EP0261854 B1 EP 0261854B1 EP 87308111 A EP87308111 A EP 87308111A EP 87308111 A EP87308111 A EP 87308111A EP 0261854 B1 EP0261854 B1 EP 0261854B1
Authority
EP
European Patent Office
Prior art keywords
rack
pinion gear
piston
pinion
bearing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP87308111A
Other languages
German (de)
French (fr)
Other versions
EP0261854A1 (en
Inventor
George Kenneth James
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bentley Motors Ltd
Original Assignee
Rolls Royce Motor Cars Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rolls Royce Motor Cars Ltd filed Critical Rolls Royce Motor Cars Ltd
Publication of EP0261854A1 publication Critical patent/EP0261854A1/en
Application granted granted Critical
Publication of EP0261854B1 publication Critical patent/EP0261854B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
    • B62D5/22—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for rack-and-pinion type

Definitions

  • the present invention relates to a rack and pinion gear particularly, but not exclusively, for a vehicle power assisted steering.
  • the rack provides equal area piston faces to supporting bearings at its opposite ends disposed in a cylinder.
  • the pinion is disposed substantially centrally with respect to the rack.
  • Turning the steering causes pressure fluid to be preferentially diverted through a valve to the appropriate piston face as a result of which the rack is assisted in the appropriate direction.
  • the provision of piston faces of equal area provides for equal power assistance on each lock.
  • Unavoidable dimensional variations of the rack and cylinder, changing stiffness of the rack as it travels past the pinion and deflections caused by service loads, particularly the offset loading of the centre takeoff lead to inconsistent rack/pinion meshing.
  • GB-A-813 312 discloses a rack and pinion gear comprising a rack which may be subject to the action of pressure fluid at either end and which is disposed in a cylinder, a pinion meshing with the rack and a first bearing for the rack adjacent to one end of the rack.
  • GB-A-1 355 811 discloses a rack and pinion gear comprising a rack which may be subject to the action of pressure fluid at either end and which is disposed in a cylinder, a pinion meshing with the rack and a first bearing for the rack adjacent to one end of the rack.
  • the rack and pinion gears described in both documents comprise a second bearing for the rack fixed to the cylinder at the position where the pinion and the rack mesh. This leads to three bearings in line, which is an unsatisfactory arrangement.
  • a rack and pinion gear for a centre take off power assisted steering arrangement comprising a rack which may be subject to the action of pressure fluid on equal piston areas at either end and which is disposed in a cylinder, a pinion meshing with the rack, a first bearing for the rack adjacent to one end of the rack, and a second bearing for the rack fixed to the cylinder at the position where the pinion and rack mesh, characterised by the rack being disposed with clearance in a floating piston at its other end.
  • the rack forms part of a centre take off power assisted steering arrangement for a vehicle.
  • a seal is provided at the said one end of the rack and the floating piston also incorporates a seal.
  • These seals each comprise a wiper seal, bearing ring and lip seal.
  • the second bearing comprises a slipper which is urged against the rack by a compression spring.
  • the spring is contained within a recess in the slipper and retained there by a plate fixed by bolts to the cylinder.
  • the steering arrangement generally comprises a rack 1 and pinion 2.
  • the rack 1 is supported in a surrounding cylinder 3 through bearings 4 and 5.
  • Pressure fluid seals 6 and 7 are associated with respective ends of the rack.
  • Pressure fluid inlets 8 and 9 lead into chambers disposed at opposite ends respectively of and partially defined by the rack 1 and cylinder 3. These inlets form part of a pressure fluid circuit which incorporates a valve which diverts pressure fluid to one end of the piston or the other depending upon the position of the steering. (Equivalent parts in Figures 1 and 2 bear the same reference numerals).
  • Bearing 4 is conventional, but bearing 5 is not.
  • Bearing 5 is shown in more detail in Figure 3. It comprises a plastics slipper 20, which is urged against the rack 1 by means of a compression spring 21. This spring 21 is accommodated in a recess in the slipper 20 and held there by a plate 22. The plate in turn is connected to the cylinder 3 by bolts 24 which extends through adjustment shims 23.
  • This bearing 5 opposes the influence of stiffness, manufacturing tolerances and service loads on the rack at precisely the point where it is likely to cause the greatest problem, that is the point at which the pinion and rack mesh.
  • the end of the rack 1 remote from the bearing 4 is provided with a floating piston arrangement.
  • this comprises a piston 30 which surrounds the end of the rack 1 with clearance.
  • the seal 7 comprises a wiper seal 31, bearing ring 32 and lip seal 33 which surround the piston 30.
  • the piston 30 is connected to the rack 1 by means of a roll pin 34 which extends through holes in both the piston and rack. This connection is not necessary during normal operation as the piston is constantly urged against the end of the rack 1 by pressure fluid (oil). However, it is necessary for quality/testing purposes where the gear is stroked in an unpressurised condition in order to maintain a specified level of residual friction. To this end the piston/seal assembly must be retained with the rack.
  • consis- tant meshing of pinion and rack is maintained and is not dependant on rack stiffness; manufacturing tolerances are compensated for and effects of service loads minimised.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Transmission Devices (AREA)
  • Power Steering Mechanism (AREA)

Description

  • The present invention relates to a rack and pinion gear particularly, but not exclusively, for a vehicle power assisted steering.
  • In a known vehicle offtake power assisted steering arrangement, the rack provides equal area piston faces to supporting bearings at its opposite ends disposed in a cylinder. In the central position of the steering, the pinion is disposed substantially centrally with respect to the rack. Turning the steering causes pressure fluid to be preferentially diverted through a valve to the appropriate piston face as a result of which the rack is assisted in the appropriate direction. The provision of piston faces of equal area provides for equal power assistance on each lock. Unavoidable dimensional variations of the rack and cylinder, changing stiffness of the rack as it travels past the pinion and deflections caused by service loads, particularly the offset loading of the centre takeoff lead to inconsistent rack/pinion meshing. Two known rack and pinion gears which may provide for power assistance are disclosed in GB-A-813 312 and GB-A-1 355 811. Specifically, GB-A-813 812 discloses a rack and pinion gear comprising a rack which may be subject to the action of pressure fluid at either end and which is disposed in a cylinder, a pinion meshing with the rack and a first bearing for the rack adjacent to one end of the rack. A similar arrangement is disclosed in GB-A-1 355 811 and the rack and pinion gears described in both documents comprise a second bearing for the rack fixed to the cylinder at the position where the pinion and the rack mesh. This leads to three bearings in line, which is an unsatisfactory arrangement.
  • According to the present invention, there is provided a rack and pinion gear for a centre take off power assisted steering arrangement comprising a rack which may be subject to the action of pressure fluid on equal piston areas at either end and which is disposed in a cylinder, a pinion meshing with the rack, a first bearing for the rack adjacent to one end of the rack, and a second bearing for the rack fixed to the cylinder at the position where the pinion and rack mesh, characterised by the rack being disposed with clearance in a floating piston at its other end.
  • Use of a floating piston in conjunction with positioning of the second bearing at the pinion allows equal area pistons either end of a rack within a cylinder to be constrained radially at two positions only. In this way meshing of the rack and pinion is not dependent on rack stiffness, manufacturing tolerances are compensated for, and the effects of service loads are minimised.
  • In a preferred embodiment of the invention, the rack forms part of a centre take off power assisted steering arrangement for a vehicle. A seal is provided at the said one end of the rack and the floating piston also incorporates a seal. These seals each comprise a wiper seal, bearing ring and lip seal. The second bearing comprises a slipper which is urged against the rack by a compression spring. The spring is contained within a recess in the slipper and retained there by a plate fixed by bolts to the cylinder. Although in normal operation the floating piston is urged against the adjacent end of the rack a connection between piston and rack is provided for testing purposes.
  • In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:-
    • Figure 1 shows a diagrammatic view of an existing centre take off power asssisted steering arrangement for a vehicle,
    • Figure 2 shows a diagrammatic view of a centre take-off power assisted steering arrangement for a vehicle according to the present invention, and
    • Figures 3 and 4 show detailed views of parts of the arrangement of Figure 2.
  • Referring to Figure 2 of the drawings, the steering arrangement generally comprises a rack 1 and pinion 2. The rack 1 is supported in a surrounding cylinder 3 through bearings 4 and 5. Pressure fluid seals 6 and 7 are associated with respective ends of the rack. Pressure fluid inlets 8 and 9 lead into chambers disposed at opposite ends respectively of and partially defined by the rack 1 and cylinder 3. These inlets form part of a pressure fluid circuit which incorporates a valve which diverts pressure fluid to one end of the piston or the other depending upon the position of the steering. (Equivalent parts in Figures 1 and 2 bear the same reference numerals).
  • Bearing 4 is conventional, but bearing 5 is not. Bearing 5 is shown in more detail in Figure 3. It comprises a plastics slipper 20, which is urged against the rack 1 by means of a compression spring 21. This spring 21 is accommodated in a recess in the slipper 20 and held there by a plate 22. The plate in turn is connected to the cylinder 3 by bolts 24 which extends through adjustment shims 23. This bearing 5 opposes the influence of stiffness, manufacturing tolerances and service loads on the rack at precisely the point where it is likely to cause the greatest problem, that is the point at which the pinion and rack mesh.
  • The end of the rack 1 remote from the bearing 4 is provided with a floating piston arrangement. Referring to Figure 4, this comprises a piston 30 which surrounds the end of the rack 1 with clearance. The seal 7 comprises a wiper seal 31, bearing ring 32 and lip seal 33 which surround the piston 30. The piston 30 is connected to the rack 1 by means of a roll pin 34 which extends through holes in both the piston and rack. This connection is not necessary during normal operation as the piston is constantly urged against the end of the rack 1 by pressure fluid (oil). However, it is necessary for quality/testing purposes where the gear is stroked in an unpressurised condition in order to maintain a specified level of residual friction. To this end the piston/seal assembly must be retained with the rack.
  • With the above described arrangement, consis- tant meshing of pinion and rack is maintained and is not dependant on rack stiffness; manufacturing tolerances are compensated for and effects of service loads minimised.

Claims (9)

1. A rack and pinion gear for a centre take off power assisted steering arrangement comprising a rack (1) which may be subject to the action of pressure fluid on equal piston areas at either end and which is disposed in a cylinder (3), a pinion (2) meshing with the rack, a first bearing (4) for the rack adjacent to one end of the rack, and a second bearing (5) for the rack fixed to the cylinder at the position where the pinion (2) and rack (1) mesh, characterised by the rack being disposed with clearance in a floating piston (30) at its other end.
2. Arackand pinion gear as claimed in claim 1, in which a seal (6) is provided at the said one end of the rack.
3. A rack and pinion gear as claimed in claim 1 or 2, in which the floating piston (30) incorporates a seal.
4. A rack and pinion gear as claimed in claim 2 or 3, in which the seal in the floating piston comprises a wiper seal (31), bearing ring (32), a lip seal (33).
5. A rack and pinion gear as claimed in any preceding claim, in which the second bearing (5) comprises a slipperwhich is urged againstthe rack (1) by a compression spring (21).
6. A rack and pinion gear as claimed in claim 5, in which the compression spring (21) is disposed in a recess in the slipper (20) and retained there by a plate (22).
7. A rack and pinion gear as claimed in claim 6, in which the plate (22) is connected to the cylinder by bolts (24) which extend through adjustment shims (23).
8. A rack and pinion gear as claimed in any preceding claim, in which the piston (30) is connected to the rack by means of a roll pin (34) which extends through holes in both the piston and the rack.
9. A centre take-off power assisted steering arrangement for a vehicle comprising a rack and pinion gear as claimed in any preceding claim.
EP87308111A 1986-09-20 1987-09-15 Rack and pinion gear Expired - Lifetime EP0261854B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8622691 1986-09-20
GB8622691A GB2196090B (en) 1986-09-20 1986-09-20 Rack and pinion gear

Publications (2)

Publication Number Publication Date
EP0261854A1 EP0261854A1 (en) 1988-03-30
EP0261854B1 true EP0261854B1 (en) 1991-01-09

Family

ID=10604515

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87308111A Expired - Lifetime EP0261854B1 (en) 1986-09-20 1987-09-15 Rack and pinion gear

Country Status (7)

Country Link
US (1) US4815552A (en)
EP (1) EP0261854B1 (en)
JP (1) JPS63101562A (en)
AU (1) AU583197B2 (en)
DE (1) DE3767258D1 (en)
ES (1) ES2020566B3 (en)
GB (1) GB2196090B (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3384105B2 (en) * 1994-05-17 2003-03-10 トヨタ自動車株式会社 Rack and pinion type steering gear device
DE19648737C1 (en) * 1996-11-25 1998-04-02 Daimler Benz Ag Steering device with hydraulic coupling, in particular for a motor vehicle
JPH1199953A (en) * 1997-09-29 1999-04-13 Trw Steering Systems Japan Co Ltd Rack-and-pinion steering system
US6098742A (en) 1998-12-14 2000-08-08 Trw Inc. Steering apparatus
JP4297575B2 (en) * 1999-11-25 2009-07-15 株式会社ショーワ Seal structure of tie rod mounting part in center take-off type power steering system
US6457375B1 (en) * 2000-07-25 2002-10-01 Terry C. Buch Rack and pinion assembly for use with steering mechanism of motor vehicles
US7401677B2 (en) * 2002-02-13 2008-07-22 Trw Inc. Self-centering steering system
FR2857324B1 (en) * 2003-07-08 2006-09-15 Koyo Steering Europe Kse BEARING FOR POWER STEERING HYDRAULIC OF MOTOR VEHICLE
DE10336628A1 (en) * 2003-08-05 2005-03-24 Thyssenkrupp Presta Steertec Gmbh Steering gear for a motor vehicle

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB813312A (en) * 1955-04-20 1959-05-13 Hydrosteer Ltd Improvements in steering mechanism
US3061036A (en) * 1959-07-23 1962-10-30 Ford Motor Co Power steering system
GB1241428A (en) * 1968-11-15 1971-08-04 Adwest Eng Ltd Rack and pinion steering mechanisms for motor vehicles
GB1355811A (en) * 1971-01-16 1974-06-05 Burman & Sons Ltd Vehicle steering gear
DE2404077A1 (en) * 1974-01-29 1975-08-07 Audi Nsu Auto Union Ag Hydraulically assisted rack and pinion steering - contains sealing element and piston connected to the rack and hydraulic line
JPS524367A (en) * 1975-06-27 1977-01-13 Matsushita Electric Works Ltd Dressing mirror
JPS55119567A (en) * 1979-03-03 1980-09-13 Nissan Motor Co Ltd Cylinder for rack type power steering
JPS55119566A (en) * 1979-03-03 1980-09-13 Nissan Motor Co Ltd Cylinder for rack type power steering
DE2931184C2 (en) * 1979-08-01 1984-01-12 Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen Rack and pinion power steering
JPS5640069A (en) * 1979-09-06 1981-04-16 Nippon Steel Corp Bottom construction of vertical furnace
DE3118254C2 (en) * 1981-05-08 1986-06-26 Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen Rack and pinion steering gear, in particular for motor vehicles
JPS59140164A (en) * 1983-01-31 1984-08-11 Atsugi Motor Parts Co Ltd Rack pinion system steering gear
DE3463479D1 (en) * 1983-03-22 1987-06-11 Bendix Espana Rack and pinion power steering, particularly with a central output
ES527577A0 (en) * 1983-11-18 1984-11-01 Bendiberica Sa AUTOMOBILE ASSISTED STEERING MECHANISM
JPS6129517A (en) * 1984-07-20 1986-02-10 Kojima Press Co Ltd Manufacture of regulator handle for vehicle
GB8425632D0 (en) * 1984-10-10 1984-11-14 Adwest Eng Ltd Rack and pinion steering mechanism
JPS6210869A (en) * 1985-07-08 1987-01-19 Toshiba Corp Fuel cell

Also Published As

Publication number Publication date
JPS63101562A (en) 1988-05-06
AU7865787A (en) 1988-03-24
US4815552A (en) 1989-03-28
ES2020566B3 (en) 1991-08-16
EP0261854A1 (en) 1988-03-30
GB8622691D0 (en) 1986-10-29
GB2196090A (en) 1988-04-20
GB2196090B (en) 1990-05-16
DE3767258D1 (en) 1991-02-14
AU583197B2 (en) 1989-04-20

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